How Much Does a Garage Conversion Cost in Seattle & the Eastside? 2026 Price Guide

Garage conversion costs in Seattle & the Eastside for 2026

For a standard two-car garage (about 400–480 sq ft), expect two distinct price tiers. Converting the garage to habitable living space — a family room, home office, gym, or bedroom with insulation, drywall, flooring, heat, and egress windows — typically runs $60,000–$120,000. Converting it to a fully self-contained ADU with a kitchen, bathroom, laundry, and separate entrance typically runs $120,000–$250,000, or roughly $250–$450 per square foot depending on utility distances and finishes. Detached garages trend toward the top of each range because water, sewer, and electrical service usually have to be trenched from the main house. Every garage conversion we build is a fixed-price, fixed-duration contract, so the number you sign is the number you pay.

What actually drives the price

Five things move a garage conversion budget more than anything else: the slab (most garage floors slope toward the door and need leveling or a new subfloor), utilities (a kitchen and bath mean new plumbing runs, and many older garages need a panel upgrade or subpanel), insulation and heating (Washington's energy code requires insulated walls, ceiling, and slab perimeter plus a heat source — usually a ductless mini-split), the garage door opening (framing, sheathing, siding, and windows to close it in), and egress — any sleeping room needs a code-sized window or door. If the structure has rot, an undersized header, or a failing roof, fixing that comes first; it's also why bids that skip a site visit aren't worth much.

Permits: what Seattle and Eastside cities require

A garage conversion is never a cosmetic project in the eyes of the city — you're changing the use of the space, so a building permit is required everywhere in King County. If you're adding a kitchen, you're creating an ADU, which brings zoning review, and thanks to Washington's HB 1337, cities including Seattle, Bellevue, Kirkland, and Redmond must allow at least two ADUs per residential lot. Seattle no longer requires replacement off-street parking in most zones, and Eastside cities have relaxed parking rules near transit. We prepare the plans, submit the permit package, and schedule every inspection — the same permit process we run on every project.

Garage conversion vs. building a DADU

A conversion wins on price: reusing the shell typically saves $100,000+ over ground-up construction, and it's faster — 2–4 months of construction versus 4–8 for a new build. A new DADU wins on layout and value: you get full-height ceilings, better siting, and a purpose-designed floor plan, which usually appraises and rents higher. If your garage is structurally sound, well-located, and you can live without the parking, convert it. If it's undersized or failing, put the money into a new build instead — we price both options side by side, and our garage conversion vs. DADU guide walks through the trade-offs in detail.

Is it worth it in 2026?

Converted garage ADUs near Seattle and Bellevue commonly rent for $1,600–$2,600 per month depending on size and finish — meaning a mid-range conversion can pay itself back in 5–8 years while adding meaningful resale value. For cost context on full ADU builds, see our 2026 ADU cost guide.

Get a fixed price for your garage

Blue Lake Construction converts garages across Seattle, Bellevue, Kirkland, Redmond, Renton, and the Eastside — design, permits, and construction under one fixed-price contract. Licensed WA GC #BLUELLC760C3. Call (206) 786-5988 or request a free consultation.